Recently, there occurs a problem of degradation in the reliability due to stress migration or electro migration, an increase in the current density, a rise in the electrical resistivity due to interface inelastic scattering of electrons and the like as interconnections are further miniaturized in an LSI interconnection structure. As an interconnection material of LSI, copper that is low-resistance metal is mainly used, but if the interconnection structure is further miniaturized, the above problem still occurs.
Therefore, use of graphene as an interconnection material of LSI is studied. It is known that graphene performs quantization conduction (so-called Ballistic conduction) and is expected as an extremely low resistance material instead of an existing metal material. Since electrons are not substantially subject to interface scattering in quantization conduction, the resistance does not substantially increase even if the interconnection structure is miniaturized.
However, in the case of polycrystalline graphene with a small grain size, a large number of crystal defects such as grain boundaries are present in the graphene.